This application relates to and incorporates herein by reference Japanese Patent Application No. 2000-392318 filed on Dec. 25, 2000.
1. Field of the Invention
The present invention relates to a rotary electric machine having a reinforcing ring on an armature.
2. Description of Related Art
It is proposed to fit a reinforcing ring on the outer periphery of an armature coil end, which protrudes from an end surface of an armature core in an axial direction, to protect the armature coil from centrifugal force. For example, in an armature 100 shown in FIG. 5, a reinforcing ring 130 is fitted on an armature coil 110 axially outside of a slot insulation paper 140 without over lapping the slot insulation paper 140. When the reinforcing ring 130 is fitted on the slot insulation paper 140 that protrudes from the side surface of the armature core 120 in the axial direction, the coil end is likely to expand in a radially outside direction due to centrifugal force by compressing the slot insulation paper 140. Therefore, it is necessary to provide a straight portion within the coil end for fitting the reinforcing ring 130 axially outside of the slot insulation paper 140 without overlapping. As a result, the axial length of the armature 100 is increased.
However, in order to downsize the rotary electric machine, it is needed to shorten the axial length of the coil end as much as possible because the coil end does not contribute to performance. Thus, mounting method of the reinforcing ring 130 must be improved to meet this requirement.
The present invention is made in view of the above problem and it is an object to provide a rotary electric machine which has a reinforcing ring on an armature and suitable for downsizing.
In an armature of the present invention, a slot insulation paper provided underneath an armature coil has a shorter axial length at an outer peripheral side of a coil end of the armature coil than at an inner peripheral side of the coil end to provide an exposed surface of the coil end at the outer peripheral side. A reinforcing ring is fitted on the exposed surface.
As compared with other armatures in which the reinforcing ring is mounted axially outside of the slot insulation paper that protrudes from the axial side surface of an armature core in the axial direction, a mounting position of the reinforcing ring is made closer to the armature core side so that the straight portion of the coil end is shortened. As a result, an axial length of the armature is shortened.
Further, a resin insulator is filled in a clearance between the exposed coil end and the reinforcing ring. Thus, it is unnecessary to accurately manage the inner diameter of the reinforcing ring.
In addition, the reinforcing ring is press-fitted in direct contact with the exposed surface of the coil end. Accordingly, the armature coil can be strengthened against the centrifugal force.